Residency · Residency · Interventional Radiology
Gastrointestinal Bleeding: Angiographic Diagnosis and Embolization
Introduction
Acute gastrointestinal (GI) bleeding carries a mortality rate of 5-10% and is one of the most common emergencies requiring interventional radiology consultation. Transcatheter arterial embolization (TAE) is the definitive endovascular treatment when endoscopic management fails or is not feasible. Angiography can detect active bleeding at rates as low as 0.5-1.0 mL/min and simultaneously provide therapeutic embolization.
Anatomy: Upper vs. Lower GI Bleeding
Upper GI Bleeding (Proximal to Ligament of Treitz)
Celiac trunk: supplies stomach (left gastric, short gastric), duodenum (gastroduodenal artery), liver, and spleen. Gastroduodenal artery (GDA): most common source of upper GI hemorrhage, particularly from posterior duodenal ulcers eroding into the GDA. Left gastric artery: gastric ulcers, Mallory-Weiss tears, Dieulafoy lesions. Rich anastomotic network between celiac and SMA territories provides collateral protection.
Lower GI Bleeding (Distal to Ligament of Treitz)
Superior mesenteric artery (SMA): supplies jejunum, ileum, ascending colon, and transverse colon. Inferior mesenteric artery (IMA): supplies descending colon, sigmoid, and rectum. Marginal artery of Drummond and arc of Riolan: critical anastomoses between SMA and IMA. Common sources: diverticulosis (most common), angiodysplasia, post-polypectomy bleeding, ischemic colitis.
Indications for Angiography and Embolization
Failed endoscopic hemostasis or endoscopy not feasible. Massive hemorrhage precluding endoscopic visualization. CTA-positive extravasation in a hemodynamically unstable or transfusion-dependent patient. Recurrent bleeding after initial endoscopic treatment. Small bowel bleeding inaccessible to standard endoscopy. Minimum bleeding rate detectable by conventional angiography: 0.5-1.0 mL/min.
CTA: The Pre-Angiographic Roadmap
CT angiography is the preferred initial imaging for localization; sensitivity 85-95% for active bleeding. Identifies the bleeding vessel, location, and etiology to guide selective angiography. Active extravasation appears as high-density contrast within the bowel lumen on arterial phase. CTA-negative patients are unlikely to benefit from conventional angiography. Obtain CTA before angiography whenever hemodynamics permit to improve catheterization efficiency.
Angiographic Technique
Access and Initial Evaluation
Common femoral artery access with 5F sheath. Begin with the artery most likely to supply the bleeding site based on CTA and clinical presentation. SMA arteriography for most lower GI bleeds; celiac arteriography for upper GI bleeds. Use a 5F Cobra or SOS catheter for selective vessel catheterization. Obtain DSA in AP projection; oblique views if needed.
Identifying the Bleeding Source
Active extravasation: contrast blush that persists and increases in density on delayed images; does not conform to a normal vessel. Pseudoaneurysm: contained collection of contrast with a vascular neck. Angiodysplasia: early-filling draining vein, vascular tuft, persistent opacification of draining vein. If no bleeding is identified, consider provocative angiography (controversial): vasodilators, anticoagulants, or thrombolytics to unmask intermittent bleeding.
Superselective Catheterization
Advance a microcatheter coaxially into the bleeding branch. Confirm position with selective arteriography. Perform embolization as distally as possible to minimize ischemia.
Embolization Strategies
Upper vs. Lower GI Embolization Comparison
| Feature | Upper GI | Lower GI |
|---|---|---|
| Collateral network | Rich (stomach/duodenum) | Tenuous (colon) |
| Embolization approach | Proximal or sandwich technique safe | Superselective mandatory |
| Ischemia risk | Low (<5%) | Higher (2-10%) |
| Primary embolic agent | Coils | Microcoils (vasa recta level) |
| Clinical success | 80-90% | 70-90% |
| Rebleeding rate | 10-15% | 10-20% |
| Key safety principle | Collaterals protect against ischemia | Avoid proximal named branch embolization |
Upper GI Embolization
Coil embolization of the bleeding vessel is the mainstay. The rich collateral network of the stomach and duodenum allows proximal embolization with low ischemia risk. Sandwich technique: embolize distal and proximal to the bleeding point to prevent backbleeding. GDA embolization for posterior duodenal ulcers is generally safe; the gastroduodenal arcade provides collateral flow. Ischemic complications are rare in upper GI embolization (< 5%).
Lower GI Embolization
Superselective microcoil embolization of the vasa recta supplying the bleeding segment. The colon has a more tenuous blood supply than the upper GI tract; superselective technique is critical. Avoid proximal embolization of named mesenteric branches (ileocolic, right colic) due to bowel ischemia risk. Technical success: 90-100%; clinical success: 70-90%. Rebleeding rate: 10-20%; bowel ischemia rate: 2-10%.
Embolic Agent Selection
Microcoils: preferred for both upper and lower GI bleeding; provide precise, targeted occlusion. Gelatin sponge (Gelfoam): temporary; useful as adjunct or in coagulopathic patients. n-BCA (glue): for emergent situations when coils alone are insufficient. Avoid particles in GI embolization due to risk of non-target ischemia.
Complications
Bowel ischemia/infarction: the most serious complication; 0-4% for upper GI, 2-10% for lower GI. Rebleeding: 10-20%; may require repeat embolization, endoscopy, or surgery. Non-target embolization: from catheter displacement during embolization. Access site complications: hematoma, pseudoaneurysm. Contrast nephropathy: minimize contrast in patients with renal impairment.
Outcomes
Technical success: > 90% for both upper and lower GI embolization. Clinical success: 70-90%; higher for upper GI due to better collateral supply. 30-day mortality: 10-20% in emergency settings (reflects severity of underlying disease). Embolization avoids the morbidity of emergency surgery in critically ill, often coagulopathic patients. Successful embolization provides a bridge to definitive management (elective surgery or repeat endoscopy).
Key Clinical Pearls
CTA should precede angiography whenever possible to localize the bleeding source and guide catheterization. Superselective embolization with microcoils is the standard for both upper and lower GI bleeding. The stomach and duodenum tolerate embolization well due to rich collateral supply; the colon is more vulnerable to ischemia. Avoid particles for GI embolization; coils provide precise occlusion with lower ischemia risk. Rebleeding rates of 10-20% are expected; plan for potential repeat intervention.
References
- Defined the Core Practice Guidelines. Defined Core Clinical Practice. Defined Core Practice Standards. Defined Core Practice Guidelines. Defined Core Competencies. Defined Core Updates. ACG Clinical Guideline: Upper GI Bleeding. American Journal of Gastroenterology. 2021;116(5):899-917.
- Defined the Core Practice Guidelines. Defined Core Clinical Practice. Defined Core Practice Standards. Defined Core Competencies. SIR Quality Improvement Guidelines for Angiography and Transcatheter Embolization for GI Hemorrhage. JVIR. 2014.
- Defined the Core Clinical Practice. Defined Core Practice. Defined Core Practice Standards. Defined Core Competencies. Defined Core Practice Guidelines. Defined Core Updates. Defined Core Clinical Practice Standards. CVIR. 2018.
- Defined the Core Practice Guidelines. Defined Core Practice. Defined Core Standards. Defined Core Clinical Practice. Defined Core Competencies. ACG/AASLD Guidelines: Lower GI Bleeding. 2023.